In conventional notebook computers, the depression key structure in a keyboard is usually supported by a collapsible mechanism and a rubber. FIG. 1 shows a typical depression key structure mounted on a base plate 10. The depression key structure 1 has a key top 11 for receiving external force and a scissors type linkage 12 which has pairs of symmetrical levers to support the depression key structure 1 and to enable the depression key structure 1 being lifted upward or pressed downward. As shown, there is a hollow rubber body 13 located under the depression key structure 1 and between the levers to provide spring energy for lifting the depression key structure 1 after the depression key structure 1 being pressed downward. The touch control circuit for the depression key structure 1 is located on the base plate 10 and under the rubber body 13 (not shown in the figure).
In the following description, only the depression key structure 1 and the collapsible linkage 12 will be shown in the figures and text. The rubber body 13 and touch control circuit will be omitted. Similar components will be marked by similar numerals any way, no matter whether or not they are in the prior arts or belong to this invention.
FIG. 2 shows a conventional collapsible mechanism 12 for the depression key structure 1. It is located between a bottom side 110 of the key top 11 and the base plate 10. It has a first lever 121 crossly engaged with a second lever 122 at a pivotal point 123 to form a substantially scissors type linkage. Two sets of such lever linkage are disposed at opposing sides under the key top 11. The first lever 121 has a first top end 1211 pivotally engaged with a first hub 1101 located under the bottom side 110 and a first bottom end 1212 rotatably and slidably engaged with a third hub 101 located on the base plate 10. The second lever 122 has a second top end 1221 pivotally and slidably engaged with a second L-shaped flange 1102 located below the bottom side 110 and a second bottom end 1222 pivotally engaged with a fourth hub 102 located on the base plate 10. The first and the second levers 121 and 122 thus form a scissors type linkage 12 that may be moved up or down under external force. The first hub 1101 and fourth hub 102 are located fixedly on a vertical dot line L.
When the key top 11 of the depression key structure 1 subjects to a downward or uplift pressure, the first top end 1211 and the second bottom end 1222 can move pivotally respectively in the first and fourth hub 1101 and 102, while the second top end 1221 and first bottom end 1212 are rotational and slidable respectively on the second flange 1102 and third hub 101. Although this structure may allow the depression key structure 1 to be lifted or lowered steadily, yet it is difficult to be manufactured and assembled. In addition, well performance of the vertical alignment of the first hub 1101 and the fourth hub 102 needs good precision in assembly. Or, a small deviation upon such alignment will create a substantial amount of lever deformation and thus make hard to fit the first top end 1211 and the second bottom end 1222 into the hubs 1101 and 102, respectively.
Furthermore, as the notebook computer is small sized and the lever 121 and 122 are generally made by plastics in thin and elongating shapes, the deformation under any possible external force during assembly could often break or rupture the levers, particularly at the force concentration points thereof at both ends of the lever or in the middle pivotal point thereof. Inevitably, such a disadvantage will drag down the production efficiency as well as the yield of the keyboard. Also, assembly and disassembly related to the depression key structure of a notebook computer is difficult. Moreover, repairs and maintenance work of such key structure are definitely time consuming.
FIG. 3 shows another conventional collapsible mechanism for depression key structure. Comparing with the one shown in FIG. 2, the main differences in between are the engagement styles for the first top end 1211 and the second bottom end 1222. A L-shaped first flange 1101 replaces the hub and a rotatable and slidable fourth hub 102 are used to replace the hub used in FIG. 2. Thus, all four ends of the fist and the second levers 121 and 122 are rotatable and slidable. As shown in this embodiment, there is no fixed vertical line alignment needed. Assembly and disassembly is also easier, by comparing with the aforesaid structure. Deformation of the levers is believed to be less severe and may reduce the possibility of breaking or rupture upon the levers.
However, due to no need of the fixed vertical line alignment upon the respective pivotal point, the levers could then move sideward. The up and down motion of the depression key structure 1 is thus less stable. Therefore, how to get a supporting mechanism of the depression key structure that enables the depression key structure 1 to move up or down steadily and may be assembled or disassembled easily is still an issue begging for improvement.